21st Century Fox has enlisted the law firm Paul, Weiss, Rifkind, Wharton & Garrison to investigate at least one accusation of sexual harassment against the Fox News host Bill O’Reilly.

The move is the latest in the response to a New York Times investigation published this month on Mr. O’Reilly’s settlements with five women who complained of sexual harassment or other inappropriate behavior.

Wendy Walsh, a former guest on Mr. O’Reilly’s show who detailed accusations against him to The Times, called 21st Century Fox’s anonymous hotline last week, prompting the investigation.

“21st Century Fox investigates all complaints and we have asked the law firm Paul Weiss to continue assisting the company in these serious matters,” the company said in a statement on Sunday.

Paul Weiss is the same law firm that conducted an internal investigation into Roger Ailes, the former Fox News chairman. 21st Century Fox executives decided to dismiss Mr. Ailes after the lawyers took statements from at least six women who described inappropriate behavior by him.

In a statement, Mark Fabiani, a spokesman for Mr. O’Reilly, said the law firm was “already retained by the company to look into all hotline calls,” adding that there was “nothing special” about the handling of this case.

It was not clear how expansive the law firm’s investigation was into Mr. O’Reilly’s behavior. 21st Century Fox has said that it investigates all claims made through the company’s anonymous hotline.

In response to the Times investigation, both Mr. O’Reilly and 21st Century Fox, the parent company of Fox News, had said that no current or former Fox News employee had raised concerns about him through the hotline. Both Mr. O’Reilly and Mr. Ailes have denied the allegations against them.

Ms. Walsh said that Mr. O’Reilly did not follow through on a verbal offer to make her a network contributor after she declined an invitation to his hotel suite following dinner one night in 2013. She said that she had not received a settlement and was not seeking one.

Her lawyer, Lisa Bloom, said that they decided to call the hotline because the company had said that nobody had done so.

“We will fully cooperate with any investigation,” Ms. Bloom said. “Again, Wendy is not seeking any money, just accountability.”